A-LevelChemistryReaction kineticsOct/Nov 2020Paper 5 Q36 Marks
A student investigates the reaction between magnesium and hydrochloric acid to determine the order of reaction with respect to hydrochloric acid. The student is supplied with 2.00 mol dm⁻³ hydrochloric acid and six identical, clean pieces of magnesium ribbon. In experiment 1, the student places 50 cm³ of 2.00 mol dm⁻³ hydrochloric acid in a 100 cm³ beaker and adds a piece of magnesium ribbon to the acid in the beaker. The student records how long it takes for the magnesium ribbon to disappear. The student carries out five further experiments, diluting the 2.00 mol dm⁻³ hydrochloric acid each time to provide results from five different concentrations of acid. The student carries out each experiment in a 100 cm³ beaker.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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